Apparatus for shrink packaging

ABSTRACT

A SHRINK TUNNEL FOR HEAT SHRINKING WRAPPING MATERIAL ABOUT ARTICLES BY INTRODUCING HEATED AND PRESSURIZED AIR THROUGH SPACED PERFORATED DISCHARGE MEMBERS WITHIN THE TUNNEL WHEREBY THE AIR IS DISTRIBUTED AGAINST AT LEAST THE TOP AND SIDES OF THE HEAT SHRINKABLE MATERIAL WITH SUBSTANTIALLY EQUALIZED VOLUME AND VELOCITY TO UNIFORMLY SHRINK THE MATERIAL AROUND THE ARTICLES.

Nov. 2, 1971 J. A. NICHOLS 3,616,543

APPARATUS FOR SHRINK PACKAGING Filed June 2, 1970 3 Sheets-Sheet 1mvnrron JOHN A. NICHOLS mr Ea Wynn, fi m/029012 d(% 60w Nov. 2, 1971 J.A. NICHOLS 3,616,543

' APPARATUS FOR SHRINK PACKAGING Filed June 2. 1970 SSheets-Sheetmvnu'ron JOHN A. NICHOLS- BY ZZ IKy fllII/MSOI? Nov. 2, 1971 Filed June2. 1970 APPARATUS A. NICHOLS 3,616,548

FOR SHRINK PACKAGING I 3 fihlewf 5 PATH DIRECTION 0 o o o o o o 0 o o oo o o o 0 l0 0 O 0 O o o 0/ N I o o 0 3| 0 P0 o o o o o ..-o o 0 o o ;oo 0 0 0 L U 3| 33 INVENTOR JOHN A. NICHOLS V hfimywz, f/e/zamm @7022504)ATTORNEYS United States Patent Office 3,616,548 Patented Nov. 2,, 19713,616,548 APPARATUS FOR SHRINK PACKAGING John A. Nichols, Canton, Mass.,assignor to Mill Industries, Inc., Shreveport, La. Continuation-impartof application Ser. No. 781,440, Dec. 5, 1968. This application June 2,1970, Ser.

Int. Cl. F26b 19/00 U.S. Cl. 34233 3 Claims ABSTRACT OF THE DISCLOSUREThis application is a continuation-in-part of the application Ser. No.781,440, filed Dec. 5, 1968, for Apparatus for Air-Treating SheetMaterial Surfaces and the Like.

This invention relates to apparatus for shrinking heat shrinkablewrapping materials about articles and more particularly to shrink tunnelapparatus in combination with a unique air distribution arrangement thatincludes spaced perforated discharge members at least along the sidewalls and along the top surface of the tunnel whereby heated air ispassed through the discharge members into the tunnel and against the topand sides of the heat shrinkable material with substantially equalizedvolume and velocity to uniformly shrink the material around thearticles.

Shrink tunnel apparatus has become increasingly popular for packagingarticles. The articles are initially covered by a loosely fitting heatshrinkable wrapping material, such as plastic, and are then passedthrough a shrink tunnel which directs heated air at a relatively highvelocity directly against the surface of the material in such a mannerthat the material shrinks to tightly engage the articles. This method ofpackaging is highly desirable since it ideally provides amoisture-proof, soil-proof and attractive package. Furthermore, if atransparent heat shrinkable material is used attractive coloring oradvertising on the articles themselves is still visible.

However, problems have arisen in the use of presently known shrinktunnels that do not equally distribute the heated air in volume andvelocity against the surfaces f the heat shrinkable wrapping material asit surrounds the articles to be packaged. Unequal and uneven volume andvelocity air-flow distribution has resulted in uneven heating andshrinking of the wrapping materials. This has resulted in packages thatare not tightly sealed and which allow moisture and direct to contactand spoil the utility or appearance of the articles. Packages that areunevenly wrapped also result in frequent damage to the articles duringtransportation thereof since loose portions of the heat shrinkablematerial are easily snagged and torn.

Thus, it is extremely important in heat-shrink packaging of articlesthat a substantially equalized volume and velocity of heated air bedistributed against the surfaces of the wrapping material so thatuniform shrinking of the material into a tight and attractive conformingfit with the articles is achieved. The present invention recognizes thisproblem and provides a unique apparatus for solving it.

Accordingly, it is an object of the present invention to provideapparatus for heat shrinking Wrapping material about articles wherebyheated air is distributed at l ast against the top and sides of thematerial with substantially equalized volume and velocity to uniformlyshrink the material around the articles.

Another object is to provide apparatus for heat-shrink packaging ofarticles whereby substantially moistureproof, soil-proof and attractivepackages are provided.

A further object of the invention is to provide apparatus for uniformlyshrinking wrapping material about articles whereby uniform shrinkage ofthe materials into a tight, attractive, conforming fit with the articlesis accomplished and whereby the number of articles wrapped per unit timeis increased as compared to presently known heat-shrink apparatus.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages are realized and obtained by means of theinstrumentalities and combinations particularly pointed out in theappended claims.

To achieve these objects the present invention provides at least alongthe side Walls and along the top surface of a heat shrink tunnel a pairof perforated discharge members spaced from one another and incommunication with a source of pressurized heated air. The heated air isdistributed with substantially equalized volume and velocity through thedischarge members against the top and sides of heat shrinkable wrappingmaterial surrounding articles to be packaged to uniformly shrink thematerial around the articles. This unique combination of a shrink tunnelwith an equalized air distribution arrangement provides uniform heatingof the heat shrinkable material and avoids localized underoroverheating. This also provides the advantage of a tightly conformingfit of the material around the articles and provides a substantiallymoistureproof, soil-proof, and attractive appearing package. Further, byuniformly distributing the heated air over the wrapping material thespeed of travel of the articles through the tunnel may be rapidlyincreased as compared with previously known tunnels without unevenheating and shrinking of the wrapping material. This, of course,markedly increases the number of articles that can be packaged per unitof time and also increases the efficiency of the packaging process.

As embodied and broadly described the invention comprises a tunnelhaving a passage formed of at least two apertured side Walls and anapertured top wall; means for transporting articles to be wrapped alonga path direction through the passage; the side and the top walls eachincluding a first chamber and a pair of perforated discharge membersspaced from one another to form a second chamber; a first one of themembers having a plurality of perforations extending in a line andsubstantially transversely of the path direction and communicatingdirectly through the perforations with the first and second chambers; asecond one of the members having staggered rows of perforations, eachrow extending substantially transversely of the path direction and theperforations in the staggered rows communicating directly with thesecond chamber and With the passage; and means for introducingpressurized, heated air into the first chamber, into the second chamberand through the first and second member perforations whereby the heatedair is distributed against the top and sides of the heat shrinkablematerial with substantially equalized volume and velocity tosubstantially uniformly shrink the material around the articles.

It should be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory but arenot restrictive of the invention.

In the drawings:

FIG. 1 is a perspective view of a shrink tunnel incorporating thefeatures of this invention;

FIG. 2 is a sectional view of the embodiment shown in FIG. 1 taken alongthe line 22 and looking in the direc tion of the arrows;

FIG. 3 is a fragmentary perspective view showing the top and a part ofone side wall of the shrink tunnel;

FIG. 4 is a detailed view of one of the pair of perforated dischargemembers of this invention; and

FIG. 5 is a detailed view of the other perforated discharge member.

With reference now to the drawings, wherein like reference charactersdesignate like or corres onding parts throughout the several views,there is shown in FIG. 1 a shrink tunnel having an outer casing 12 and apassage therethrough formed of two side walls 14 and a top surface 16.

Means are provided in operative relationship with the tunnel fortransporting articles along a path direction through the passage. Ashere embodied, the transporting means is conveyor assembly 18 thatincludes lateral supporting members 22 mounted on endless belts 20whereby the articles 24 to be packaged are transported by the conveyoralong a predetermined path direction through the passage.

The side walls 14 and top wall 16 of the tunnel are similar in structureand for convenience only the top wall construction will be explained indetail, it being understood that the side walls are constructed in asimilar manner. The relationship between the side walls and the top wallis best illustrated in FIG. 2.

In accordance with a preferred embodiment of the invention, top surface16 includes a first chamber 26 and a pair of perforated dischargemembers 31 and 33 vertically spaced from one another to form a secondchamber 34. Member 31 has a pluralit of perforations 31' formed in aline that extends substantially transversely of the path direction. Theperforations communicate directly with first chamber 26 and with secondchamber 34. The second one of the members 33 has a staggered row ofperforations 33 that also extends substantially transversely of the pathdirection. Each of the perforations 33' communicates directly withsecond chamber 34 and with the passage of the tunnel. Preferably,perforations 33 are offset from and are placed on alternating sides ofan imaginary midline that is located directly below the row ofperforations 31' in first member 31. This greatly enhances the equaldistribution of air flow within the passage and avoids the straightuninterrupted flow of air from perforations 31' through perforation 33'.

Means are also provided in fluid communication with first chamber 26 forintroducing pressurized heated air into the first chamber, into secondchamber 34 and through the first and second member perforations wherebythe heated air is distributed against the top and sides of the heatshrinkable material surrounding the articles 24 with substantiallyequalized volume and velocity to substantially uniformly shrink thematerial around the articles. As here embodied, the introducing meansare ducts 36 and 36' that are preferably connected to a source of heatedair (not shown). The pressurized hot air is directed through ducts 36and 36', through first perforated discharge members 31 that extendtransversely across the path direction and through second perforateddischarge members 33 that also extend transversely across the pathdirection. By using second perforated discharge members 33 spaced fromfirst discharge members 31, the pressurized air is caused to bedischarged uniformly across the heat shrinkable material as the articlespass through the tunnel, and the heated air is evenly distributed acrossthe material in substantially equalized volume and velocity.

The invention, thus, provides an unique air distribution system incombination with a shrink tunnel whereby heated air is distributedagainst the top and sides of heat shrinkable wrapping materialsurrounding articles to be packaged and whereby a substantiallyequalized volume and velocity of heated air is applied uniformly to thematerial so that it shrinks in a uniform manner to provide asubstantially moisture-proof, soil-proof and attractive package.

The invention in its broader aspects is not limited to the specificdetails as shown and described and departures may be made from suchdetails without departing from the principles of the invention andwithout sacrificing its chief advantages.

What is claimed is:

1. Apparatus for shrinking heat shrinkable material about articles,comprising:

a tunnel having a passage formed of at least two side walls and a topsurface;

means in operative relationship with said tunnel for transporting saidarticles along a path direction through said passage;

said side walls and said top surface each including a first chamber anda pair of perforated discharge members spaced from one another to form asecond chamber;

a first one of said members having a plurality of perforations extendingin straight lines substantially transversely of said path direction andcommunieating directly through said perforations with said first andsecond chambers;

a second one of said members having staggered rows of perforations, saidrows extending substantially transversely of said path direction andsaid perforations in said staggered rows communicating directly withsaid second chamber and with said passage; and

means in fluid communication with said first chamber for introducingpressurized, heated air into said first chamber, into said secondchamber and through said first and second member perforations wherebythe heated air is distributed against the top and sides of said heatshrinkable material with substantially equalized volume and velocity tosubstantially uni formly shrink said material around said articles.

2. Apparatus as in claim 1 wherein the perforations in said seconddischarge member are offset from and are placed on alternating sides ofan imaginary midline that is located directly below each row of saidperforations in said first discharge member.

3. Apparatus as in claim 2 wherein the first chambers in each of saidside walls and said top surface are in fluid communication with eachother.

References Cited UNITED STATES PATENTS 2,334,232 11/1943 Wells 34-233 X3,222,800 12/1965 Siegel et al. 34-225 X 3,309,835 3/1967 Peppler 34225X 3,399,506 9/1968 Howe 34225 X CARROLL B. DORITY, JR., Primary Examiner

